1. Technical Field
The present invention relates to a shelf-stable soft pretzel and, in particular, to a soft pretzel product that maintains appearance, texture and taste over a long shelf life. The invention substitutes a number of preparation steps in place of the traditional caustic bath preparation step in order to lower the pretzel""s pH in addition to other microbal spoilage hurdle strategies.
2. Description of Related Art
Soft pretzels have become one of the most popular bread snacks in the baking and food service industries. In the past, soft pretzels were a highly regional food, limited mostly to the Northeastern United States, but the popularity of soft pretzels has spread significantly both nationally and internationally during the past decade. This popularity comes from the fact that soft pretzels are typically made from a low fat, lean formula dough resulting in a healthy snack with good flavor and desirable eating characteristics.
Traditionally made, shelf-stable, soft pretzels exhibit a very poor shelf life and are quite susceptible to both microbal spoilage and staling. Use of chemical preservatives is ineffective in traditionally made soft pretzels because of a relatively high final surface pH, typically a pH of approximate 8. Chemical preservatives work best in a low pH environment and are usually not particularly effective above a pH of 6. The surface pH on a traditionally made soft pretzel is alkaline because of a necessary caustic bath or cook step. The critical role that the caustic bath step plays in making a pretzel is explained in more detail below.
Another problem encountered when trying to extend the shelf life of a soft pretzel is the fact that soft pretzels, as is typical of most soft bread products, exhibit a high water activity. (xe2x80x9cWater activityxe2x80x9d is the partial pressure of water in a food divided by the partial pressure of pure water under the same conditions.) If the fresh pretzel is packaged, this high water activity will soon translate into a high moisture content within the package. The presence of water vapor in the package promotes dissolving of the topical salt and eventually to a softening of the pretzel""s crust. High water activity also promotes microbal spoilage.
As with other bread products, staling is also a problem encountered when attempting to store a soft pretzel for an extended period. While the effects of staling can be partially reversed by re-heating the pretzel, eventually the staling reaches a point that makes re-heating an ineffective remedy.
The problems encountered when attempting to extend the shelf life of a soft pretzel can be further understood by reviewing the processing for making a traditional soft pretzel. FIG. 1 is a flow chart showing the typical prior art method of making a soft pretzel. The first step is the dough preparation or mixing step 100, which involves combining various dough ingredients in the proper proportions as is well known in the food and baking industries. The pretzel dough is then physically manipulated to a desired pretzel shape in a product formation step 110. The product formation step 110 can be performed by any number of means well known in the art, such as twisting by extruders, hand twisting or shaping, or by the use of rolling devices. The pretzel dough is then dipped into a caustic or alakli bath 120, typically with a pH of over 12 and consisting of, for example, a two percent caustic solution at 165xc2x0 farenheit. This caustic bath or cooking step 120 is often performed in what is referred to in the industry as a xe2x80x9cpretzel cooker.xe2x80x9d
This caustic bath step 120 ultimately produces a number of effects which give rise to many of the distinctive features of a traditional soft pretzel. For example, the caustic bath step 120 promotes the uniform browning of the exterior of the pretzel. The caustic bath step 120 also imparts a unique flavor to the pretzel. Importantly, the caustic bath step 120 gelatinizes the starch of the pretzel. Starch gelatinization is the irreversible heat-induced change in a starch granule characterized by water uptake, swelling, and viscosity increases. The starch gelatinization produced by the caustic bath step 120 promotes the characteristic glossy and smooth finish of the exterior of the pretzel and provides a sticky surface for adhering granular salt during the salting step 130.
After the salting step 130 the pretzel then goes through a baking step 140 followed by a cooling step 150. Finally, unless the pretzel is consumed shortly after preparation, the pretzel must be packaged 160.
Without the effective presence of chemical preservatives, precluded by the high alkalinity imparted during the caustic bath, and in light of the high water activity found in a traditional soft pretzel, soft pretzels typically demonstrate a shelf life of less than a week. Such a short shelf life makes a soft pretzel product a poor candidate for retail distribution of the pretzel as a packaged product. By comparison, soft bagels, which have been successfully marketed as a relatively shelf-stable product, typically maintain color, texture, and taste for a period of two to three weeks. A soft pretzel product has yet to demonstrate a shelf life approaching that of bagels and other like products without sacrificing taste, color, and texture, thus making the prospect of mass marketing not economically viable or practical.
Attempts to extend the shelf life of soft pretzels have met with limited success resulting in mold spoilage and color degradation over time. Approaches to this issue have included lowering the surface pH slightly by de-emphasizing the caustic bath and lowering the water activity of the finished product. The latter is disclosed by U.S. Pat. No. 4,803,084 (xe2x80x9cShinexe2x80x9d). Reducing the alkalinity of the pretzel only slightly, such as to the range of a pH of 6 to 7 does not increase the effectivity of chemical preservatives to the extent required to obtain a sufficiently long shelf life. Reducing the water activity alone, as in Shine, also only increases the shelf life for the pretzel slightly. Further, unless the water activity is lowered to the range of 0.73 or below the granular salt will turn into brine. It is also doubtful that the bread characteristics of a pretzel can be maintained at such a low water activity.
Accordingly, a need exists for a shelf-stable soft pretzel. This shelf-stable soft pretzel should demonstrate the characteristic look, texture, and taste of a traditional soft pretzel and yet be highly resistant to microbal spoilage and capable of maintaining a fresh taste and appearance, without color degradation, even when the product is exposed to regular atmosphere over an extended period. Further, the shelf-stable soft pretzel should not promote dissolving of the topical salt granules despite a high humidity content of the package or container.
The proposed invention comprises a method for preparing a shelf-stable soft pretzel by substituting various processing steps for the caustic bath step found in the traditional soft pretzel preparation and other microbal spoilage hurdle strategies. A steam or hot water step is combined with the application of a browning agent prior to baking the pretzel. A methyl-cellulose top coat is then applied followed by the topical application of enrobed salt. The product then undergoes a low temperature drying step prior to packaging. By eliminating the need for a caustic bath, food preservatives can be added to the dough preparation. The final surface pH has been demonstrated at less than 5.5, thus providing a suitable environment for the effectiveness of chemical preservatives. An anti-staling enzyme is also added to the dough prior to baking. Further, the enrobed salt is resistant to dissolving despite the presence of excess water vapor in any product packaging.
The end result is a shelf-stable soft pretzel which maintains the appearance, taste, and texture of a traditional soft pretzel, with resistance to microbal spoilage and color degradation, over a shelf life in excess of six weeks.
The above as well as additional features and advantages of the present invention will become apparent in the following written detailed description.